[PATCH 4.9 108/271] media: tw5864: Fix possible NULL pointer dereference in tw5864_handle_frame

[Greg Kroah-Hartman]

From: YueHaibing <yuehaibing@xxxxxxxxxx>

[ Upstream commit 2e7682ebfc750177a4944eeb56e97a3f05734528 ]

'vb' null check should be done before dereferencing it in
tw5864_handle_frame, otherwise a NULL pointer dereference
may occur.

Fixes: 34d1324edd31 ("[media] pci: Add tw5864 driver")

Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/media/pci/tw5864/tw5864-video.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/pci/tw5864/tw5864-video.c b/drivers/media/pci/tw5864/tw5864-video.c
index 1ddf80f85c248..27ff6e0d98453 100644
--- a/drivers/media/pci/tw5864/tw5864-video.c
+++ b/drivers/media/pci/tw5864/tw5864-video.c
@@ -1386,13 +1386,13 @@ static void tw5864_handle_frame(struct tw5864_h264_frame *frame)
 	input->vb = NULL;
 	spin_unlock_irqrestore(&input->slock, flags);
 
-	v4l2_buf = to_vb2_v4l2_buffer(&vb->vb.vb2_buf);
-
 	if (!vb) { /* Gone because of disabling */
 		dev_dbg(&dev->pci->dev, "vb is empty, dropping frame\n");
 		return;
 	}
 
+	v4l2_buf = to_vb2_v4l2_buffer(&vb->vb.vb2_buf);
+
 	/*
 	 * Check for space.
 	 * Mind the overhead of startcode emulation prevention.
-- 
2.20.1